R语言数据整理技巧(1)-读写、数据类型、重构

1、读取和写入数据：xlsx；txt; rdata

path=C:\\Users
setwd(path)
#读取
#读取csv
read.csv(.csv)
#读取txt
read.txt(.txt)
#读取剪贴板
read.table("clipboard")
#读取xlsx
library(readxl)
read_xlsx(.xlsx)
#读取rdata文件
load(.radta)
#写入
#写入csv
write.csv(data,file="filename.csv",quote=F）
#写入rdata
save(data,file="filename.rdata")
#写入xlsx
library(xlsx)
write.xlsx(data,file="filename.xlsx")

2、批量转化数据类型

# 生成一个包含三个字符串型的data.frame
df <- data.frame(
  # 数字
  num1= c("1", "2", "3"),
  num2 = c("1", "2", "3"),
  # 字母
  letter1 = c("a", "b", "c"),
  letter2 = c("d", "e", "f"),
  #单词
  word = c("hello", "world", "goodbye")
)
#批量将字符串类型转化为因子类型
df[sapply(df, is.character)] <- lapply(df[sapply(df, is.character)], as.factor)
#批量将字符串转化为数值型
df[,1:2]<-sapply(df[,1:2],as.numeric)

3、表格转置、整合、融合、重铸

df_t<-t(df)#转置
agg<-aggregate(df,by=list(num1),FUN=mean,na.rm=TRUE)#整合
library(reshape2)
df_me<-melt(df,id=c("num1","num2"))#融合
decast(df_me,num1+num2~variable)#重铸